The negativity is because Tesla has some truly abhorrent business practices. For me, it's out of love, not hate. Of course, there's a lot of people who stand to gain from Tesla failing.
I’ve heard he doesn’t pay well. It would be a lot easier to support a “visionary” if they believed in treating their employees well. Henry Ford did it a century ago. We probably got a golden age (of sorts) out of that.
And it might sound callous but plenty of companies have similar practices (and are not creating anything of earth-shattering value), so judging Tesla more than the others is a bit unfair.